接着《XNA试验篇(二)》，我们现在将程序修改为为以下（注意“新增2”与“删除新增”）：
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
namespace MyFirstGame
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
/// <summary>
/// 定义一个Texture2D的对像（新增）
/// </summary>
Texture2D texture;
/// <summary>
/// 定义图片坐标（新增2）
/// </summary>
Vector2 picPosition;
/// <summary>
/// 游戏界面的宽度（新增2）
/// </summary>
int clientW = 0;
/// <summary>
/// 游戏界面的高度（新增2）
/// </summary>
int clientH = 0;
/// <summary>
/// 存放按键情况（新增2）
/// </summary>
List<Keys> keysList;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
keysList = new List<Keys>();//（新增2）
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
//新增
//等控件初始化完成后，graphics.GraphicsDevic就不会为NULL了
//将test.jpg的图片以2D的方式画到当前的graphics.GraphicsDevice
texture = Texture2D.FromFile(graphics.GraphicsDevice, "test.jpg");
int picW = texture.Width;//获取加载图片的宽度
int picH = texture.Height;//获取加载图片的高度
clientW = graphics.GraphicsDevice.Viewport.Width;//设置游戏界面的宽度
clientH = graphics.GraphicsDevice.Viewport.Height;//设置游戏界面的高度
int centerX = (clientW - picW) / 2;//求出游戏界面的X坐标中心点
int centerY = (clientH - picH) / 2;//求出游戏界面的Y坐标中心点
picPosition = new Vector2(centerX, centerY);
// TODO: use this.Content to load your game content here
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <summary>
/// Allows the game to run logic such as updating the world,
/// checking for collisions, gathering input, and playing audio.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
//（新增2）开始
KeyboardState keyboardstate = Keyboard.GetState();//获取键盘输入的键，会保持上一次按键状态
Keys[] keys = keyboardstate.GetPressedKeys();//
foreach (Keys key in keys)
{
if (keysList.Count == 0)
{//使用当时的按键
KeyBoardHandle(key);
}
else
{
//采用存起来的按键
foreach (Keys k in keysList)
{
if (key == k)
continue;//跳出与当前按键重复
KeyBoardHandle(k);
}
}
}
keysList.Clear();
foreach (Keys k in keys)
keysList.Add(k);
////（新增2）结束
// TODO: Add your update logic here
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
// TODO: Add your drawing code here
//新增
//绘画驱动开始
spriteBatch.Begin();
//将texture加载的图片画到所属的GraphicsDevice上，并定义图片所在的2维坐标，以及图片的着色颜色。
//spriteBatch.Draw(texture, new Vector2(0.0f, 0.0f), Color.Red);//(取消新增)
spriteBatch.Draw(texture, picPosition, Color.White);//（新增2）
//结束GraphicsDevice绘画
spriteBatch.End();
base.Draw(gameTime);
}
#region 处理键盘按键（新增2）
private void KeyBoardHandle(Keys key)
{
switch (key)
{
case Keys.Up:
//按向上键的时候
MoveUp();
break;
case Keys.Down:
//按向下键的时候
MoveDown();
break;
case Keys.Left:
//按向左键的时候
MoveLeft();
; break;
case Keys.Right:
//按向右键的时候
MoveRight();
; break;
}
}
#endregion
#region 移动图片（新增2）左上角的坐标{0,0},向右Y坐标增加，向下X坐标增加
/// <summary>
/// 图片向上移动
/// </summary>
private void MoveUp()
{
if (picPosition.Y > 0)//控制移动边界
picPosition.Y -= 5;//向上移动5个单位
}
/// <summary>
/// 图片向下移动
/// </summary>
private void MoveDown()
{
if (picPosition.Y < clientH - texture.Height)//控制移动边界
picPosition.Y += 5;//向下移动5个单位
}
/// <summary>
/// 图片向左移动
/// </summary>
private void MoveLeft()
{
if (picPosition.X > 0)//控制移动边界
picPosition.X -= 5;
}
/// <summary>
/// 图片向右移动
/// </summary>
private void MoveRight()
{
if (picPosition.X < clientW - texture.Width)//控制移动边界
picPosition.X += 5;
}
#endregion
}
}
我们需要注意的重要地方有：
KeyboardState keyboardstate = Keyboard.GetState();//获取键盘输入的键状态
Keys[] keys = keyboardstate.GetPressedKeys();//获取当前按键信息，在键盘没有按任何键的时候会保持上一次按键状态
请看注释即可。因为都是比较容易一些的函数来的。呵呵